Tail terms: diagram \((b)\)  in Fig.REF , are processes where a Gravitational Wave is emitted by the binary system and scattered off the quasi-static curvature into the same GW source. The dotted line denotes a graviton attached to a conserved charge, which imply that the corresponding Green's function has exactly zero time component momentum. They contribute to the conservative dynamics starting at 4PN as first noticed in [1]}, [2]}, and in the context of EFT in [3]}.
